The present invention relates generally to medical devices and methods. More specifically, the invention relates to catheter devices and methods for delivering a medical device to a location within a patient's body.
One of the most pervasive trends in modern medicine and surgery is the development of devices and methods for performing minimally invasive procedures. For example, balloon angioplasty and stent placement are techniques that were developed as alternatives to open heart, coronary artery bypass procedures. Arthoscopic surgical procedures have been developed in orthopedics for performing various surgical procedures on the knee, shoulder and other joints through small incisions, thus avoiding traditional, open surgical techniques. Laparoscopic surgical procedures have been developed for gall bladder removal and other intra-abdominal surgeries, to reduce trauma and speed recovery time by requiring only small incisions and minimal abdominal wall trauma. Developments in the minimally invasive arena have even evolved toward robotic surgical systems, such as the da Vinci® Surgical System provided by Intuitive Surgical, Inc. (Sunnyvale, Calif.), which allows a surgeon to remotely perform operations ranging from prostate or gall bladder removal to coronary bypass. Hundreds, if not thousands, of new minimally invasive techniques are still being developed. For example, a number of established and start-up medical device companies are developing techniques for repairing or replacing heart valves, ablating portions of the heart to treat arrhythmias, and performing other cardiac procedures using catheter-based devices.
Other examples of a minimally invasive procedures, devices and systems are described in U.S. patent application Ser. Nos. 10/671,191, 10/833,950 and 10/915,716, which were incorporated by reference immediately above. Generally, these methods and devices involve placing a device in a patient's stomach (and sometimes placing a portion of the device across the pyloric valve of the stomach in the duodenum) to treat or ameliorate obesity and/or to perform any of a number of other functions, such as to help treat other gastrointestinal disorders.
Many of the newly developed minimally invasive techniques, and many that will be developed in the future, involve using a catheter device to deliver a therapy within a patient's body. Some techniques, such as placing stents in a coronary artery to prop open the artery, involve delivering a medical device (in this case a stent) from the distal end of the catheter. In another example, a device may be placed into the stomach and/or the duodenum via a catheter advanced through the patient's esophagus. In many cases, delivering medical devices to locations within the body using a long, flexible catheter may be difficult or awkward. For example, it may be difficult to sufficiently control advancement of a long, flexible, low-profile catheter to position a distally-housed medical device in a desired location in the body. Even once the distal end of the catheter is advanced to a desired position, it may be difficult to release the medical device from the catheter in precisely the desired location and orientation. Releasing the device may even damage the device and/or nearby delicate human tissue, in some cases.
For example, delivering a medical device via an elongate catheter often involves sliding the device out of the catheter. Friction between sliding surfaces of the medical device and the delivery catheter complicates delivery of the device, especially when the catheter is curved to follow a tortuous pathway, such as a coronary blood vessel. In the case of stent delivery, for example, stent delivery from the distal end of a delivery catheter typically involves pushing the stent out of the catheter and/or retracting the catheter proximally relative to the stent, while holding the stent in place, all actions which may damage the stent. Furthermore, a stent is compressed or collapsed to fit within the catheter, thus storing energy in the stent. When the stent is released, the stored energy may often cause it to propel forward to an undesired location. Additionally, such a delivery catheter requires a pusher device for pushing the stent out or holding it stable while a portion of the catheter is retracted and/or a retractable sheath or sleeve, both of which complicate manufacturing of the delivery device and necessitate a larger delivery device profile. Catheter-based delivery of other medial devices to various locations in the body, such as placing a device in the stomach, pyloric valve and/or duodenum, may face similar challenges.
Therefore, a need exists for effective, minimally-invasive or non-invasive devices and methods for delivering medical devices within a patient's body. Ideally, such devices and methods would be relatively easy to use and allow for atraumatic delivery of a medical device to a desired location without damaging the medical device or the delivery device. Also ideally, such delivery devices would be relatively low-profile and allow for precise device placement at the desired location in the body. At least some of these objectives will be met by the present invention.